Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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230
FXUS62 KRAH 140539
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1240 AM EST SUN FEB 14 2016

.SYNOPSIS...ARCTIC HIGH PRESSURE WILL EXTEND ACROSS THE AREA
TODAY. A DEVELOPING STORM SYSTEM WILL APPROACH FROM THE WEST TONIGHT
AND MOVE EASTWARD ACROSS THE REGION MONDAY THROUGH TUESDAY. HIGH
PRESSURE WILL GRADUALLY BUILD IN FROM THE NORTHWEST TUESDAY
NIGHT AND WEDNESDAY.
&&

.NEAR TERM /THROUGH SUNDAY/...
AS OF 930 PM SATURDAY...

1036MB SURFACE HIGH OVER INDIANA/OHIO WILL BUILD ACROSS THE
APPALACHIANS AND VIRGINIA OVERNIGHT...WITH THE RIDGE AXIS SHIFTING
OVER CENTRAL NC LATE TONIGHT.  LOW-LEVEL THICKNESSES ARE EXPECTED TO
DROP TO AROUND 1240M...WHICH SHOULD RESULT IN SOME SINGLE DIGIT LOWS
IN OUTLYING AREAS.  HIGH CLOUDS ACCELERATING THROUGH THE MID-
MISSISSIPPI RIVER VALLEY WILL REACH THE WESTERN CWA LATE TONIGHT AS
WELL...AND THE UPPER LEVEL PATTERN SUGGESTS SOME OROGRAPHIC
ENHANCEMENT IS POSSIBLE AS NORTHWEST FLOW INCREASES ACROSS THE
APPALACHIAN RIDGES.  RIGHT NOW GUIDANCE INDICATES THE CLOUDS WILL BE
HIGH AND THIN AT FIRST...WITH MORE SUBSTANTIAL MID CLOUDS TO FOLLOW
LATER IN THE MORNING.  THIS FORECAST UPDATE WILL LOWER MIN TEMPS A
FEW DEGREES IN THE TYPICALLY COLDEST SPOTS OF THE PIEDMONT AND
COASTAL PLAIN...WITH LOWS RANGING FROM 9-15.  SINGLE DIGIT WIND
CHILLS FOR MOST AREAS.

SUNDAY: ON SUNDAY SURFACE HIGH PRESSURE MOVES DIRECTLY OVERHEAD AND
THE UPPER LEVEL FLOW BECOMES VERY ZONAL. THIS WILL ALLOW WINDS TO
CALM AND SKIES TO REMAIN CLEAR FOR THE MORNING...BUT IT ALSO MEANS
THAT THE ARCTIC AIR THAT WAS BROUGHT INTO PLACE TODAY WILL HAVE VERY
LITTLE PLACE TO GO AND TEMPERATURES WILL REMAIN VERY COLD WITH
EXPECTED HIGHS ON SUNDAY ONLY IN THE LOW TO MID 30S. FURTHER
HINDERING ANY EFFECTS OF INSOLATION...A MID-LEVEL CLOUD DECK WILL
MOVE IN FROM THE WEST DURING THE AFTERNOON HOURS SO WE WONT GET ANY
HELP WITH TEMPERATURES THERE...PERHAPS IN THE EAST WHERE IT WILL
TAKE LONGER TO OVERSPREAD THE AREA. NO PRECIPITATION IS EXPECTED

&&

.SHORT TERM /SUNDAY NIGHT THROUGH WED NIGHT/...
AS OF 320 PM SATURDAY...

...WINTRY WEATHER STILL EXPECTED SUN NIGHT/MON/MON NIGHT ESPECIALLY
OVER THE NC PIEDMONT...

SUN NIGHT THROUGH TUE:

OVERVIEW: CONFIDENCE CONTINUES TO INCREASE REGARDING THE TIMING...
MOST PROBABLE PRECIP TYPE PATTERN... AND PRIMARY WEATHER THREATS FOR
THE INCOMING SYSTEM. LATEST GUIDANCE SHOWS THE ONSET OF PRECIP SUN
NIGHT MOSTLY AFTER MIDNIGHT... AND AN EARLIER ENDING BY THE LUNCH
HOUR TUE. LONGWAVE TROUGHING WILL CONTINUE TO AMPLIFY ALONG THE MISS
VALLEY SUN NIGHT/MON AS NRN STREAM ENERGY DROPS INTO ITS BASE OVER
THE GULF STATES... CULMINATING IN A NARROW DEEP SHORTWAVE TROUGH
TAKING ON A SLIGHT POSITIVE TILT AS IT SWINGS ENE THROUGH THE
CAROLINAS/VA LATE MON NIGHT THROUGH TUE MORNING. AT THE SURFACE...
THE POLAR HIGH SITUATED OVER THE NORTHEAST AND MIDATLANTIC STATES
SUN NIGHT WILL PUSH STEADILY NORTHEAST AND OUT OVER THE NW ATLANTIC
THROUGH MON... WHILE A COASTAL FRONT FORMS ALONG THE CAROLINA COAST
EXTENDING BACK TO DEVELOPING LOW PRESSURE OVER THE CENTRAL GULF
STATES. THIS LOW THEN TRACKS EAST THEN NE THROUGH NC MON EVENING
THROUGH EARLY TUE MORNING BEFORE MOVING QUICKLY INTO THE NORTHEAST
STATES... WITH A TRAILING FRONT SWEEPING OFF THE NC COAST BY EARLY
TUE AFTERNOON. SOME UNCERTAINTY PERSISTS REGARDING THE PATTERN OF
CYCLOGENESIS BUT IT`S LOOKING MORE LIKE A MILLER-A WITH THE COASTAL
FRONT JUMPING INLAND MON NIGHT AND A PRIMARY LOW TRACKING
NORTHEASTWARD ALONG THIS FRONT EAST OF THE APPALACHIANS. WHILE THE
SURFACE HIGH WILL HAVE INITIALLY DEPOSITED PLENTY OF COLD STABLE
AIR... THE HIGH ITSELF WILL BE TRANSITORY AND THE STABLE POOL SHOULD
EVENTUALLY BECOME VULNERABLE TO THE STRENGTHENING WARM NOSE AT 850-
900 MB.

PRECIPITATION CHANCES: AT THE BEGINNING OF THE EVENT... THE
PROCESSES TO FORCE ASCENT SUNDAY NIGHT INTO EARLY MONDAY INCLUDING
DPVA AND MOIST ISENTROPIC UPGLIDE ARE RATHER WEAK AND FOCUSED
PRIMARILY ON WRN AND NRN PORTIONS OF CENTRAL NC. IT WILL ALSO TAKE A
FEW HOURS FOR THE INITIALLY DRY SUBCLOUD LAYER TO MOISTEN SUN NIGHT.
WILL TREND POPS UP TO LIKELY IN THE NW WITH LOWER CHANCE POPS TO THE
SOUTH AND EAST SUN NIGHT... THEN EXPAND POPS TO THE EAST AND SOUTH
TO LIKELY S/E AND CATEGORICAL NW DURING MON... BUT WITH FAIRLY LIGHT
QPF... UNDER A QUARTER INCH MAINLY IN THE NW FOR THE SUN NIGHT/MON
PERIOD. THIS CHANGES HOWEVER MON EVENING/NIGHT AS STRONG UPPER
DIVERGENCE (DUE TO IDEALLY JUXTAPOSED POLAR AND SUBTROPICAL JETS)
AND VIGOROUS LOW LEVEL MOISTURE TRANSPORT EAST OF THE LOW STRENGTHEN
DEEP LAYER LIFT. WILL RAMP UP POPS FURTHER TO CATEGORICAL
WEST/LIKELY EAST LATE MON... THEN TO CATEGORICAL EVERYWHERE MON
NIGHT INTO TUE MORNING... ENDING W TO E MID MORNING THROUGH EARLY
TUE AFTERNOON.

PTYPES: USING THE TOP-DOWN METHODOLOGY WITH CONSIDERATION OF (A) THE
INITIALLY VERY COLD/DENSE NATURE OF THE SURFACE AIR MASS... (B) THE
STRENGTHENING WARM NOSE ALOFT... AND (C) THE STRONG LOW LEVEL WARM
ADVECTION AND WARM HYDROMETEORS ALOFT THAT SHOULD DISLODGE/DISSOLVE
THE WEDGE AIR MASS SE TO NW MON AFTERNOON/EVENING... EXPECT THIS TO
START AS MOSTLY LIGHT SNOW WITH PERHAPS PATCHY LIGHT SLEET SUN NIGHT
ACROSS THE NRN AND WRN CWA... FOLLOWED BY A TRANSITION FROM SSE TO
NNW TO FREEZING RAIN/SLEET THEN TO ALL RAIN... WITH THE FAR NW
COUNTIES INCLUDING THE TRIAD THE LAST TO SEE AN END TO THE WINTRY
PRECIP MON EVENING. THE LATEST MODEL TIMING AND VERTICAL THERMAL
STRUCTURE SUGGESTS A SLIGHTLY LONGER-LASTING AND MORE AREALLY
EXPANSIVE ICING THREAT THAN WHAT WAS INDICATED YESTERDAY... ALTHOUGH
THIS OVERALL LOOKS LIKE ADVISORY CRITERIA ACCUMULATIONS AT MOST OVER
ALL BUT PERHAPS THE FAR NW. TENTATIVE ACCUMULATIONS WILL BE FROM ONE
TO THREE HUNDREDTHS OF AN INCH OF ICING (MAINLY TRACE AMOUNTS)
ALONG/NW OF HIGHWAY 1 EXCEPT FOR FOUR TO SIX HUNDREDTHS IN THE NW
PIEDMONT... AND SNOW TOTALS OF 1-3" NW QUARTER WITH A QUARTER INCH
TO ONE INCH ELSEWHERE (JUST A TRACE SE)... ALL OF WHICH SHOULD BE
QUICKLY SWEPT AWAY BY MODERATE TO POTENTIALLY HEAVY RAINFALL MON
NIGHT INTO TUE MORNING. WILL ISSUE A WINTER STORM WATCH FOR AREAS
ALONG AND NW OF A LINE FROM ALBEMARLE TO CARTHAGE TO RALEIGH TO
WARRENTON FOR SUN NIGHT THROUGH LATE MON.

PRECIP TOTALS: STORM TOTAL LIQUID QPF IS EXPECTED TO BE 1 TO 1 1/2"
WITH LOCALLY HIGHER AMOUNTS POSSIBLE... GIVEN THE HIGH WATER CONTENT
AND STRONG LIFT MON NIGHT/TUE MORNING. BASED ON THE ANTECEDENT
CONDITIONS AND WITH SEVERAL RIVERS AND CREEKS RUNNING HIGH... A
FLOOD WATCH MAY BE NEEDED FOR SOME PORTION OF THE AREA FOR MON NIGHT
INTO TUE MORNING.

STORM POTENTIAL: WHILE LAPSE RATES WILL LIKELY BE MARGINAL (NEARING
6.5 C/KM LATE MON NIGHT INTO TUE MORNING MAINLY IN THE EAST)... THE
STRONG AND FOCUSED LIFT POSSIBLE WITH THIS SYSTEM AND WARMING LOW
LEVELS ESPECIALLY IN THE SANDHILLS AND COASTAL PLAIN MAY SUPPORT A
FEW LIGHTNING STRIKES LATE MON NIGHT INTO TUE MORNING.

TEMPS: EXPECT LOWS SUN NIGHT OF 22-27. TEMPS SHOULD SLOWLY RISE MON
THROUGH MON NIGHT... REACHING THE LOW 30S NW TO LOW 40S SE LATE
MON... RISING TO THE MID 30S NW TO UPPER 40S SE MON NIGHT... AND
PEAKING AT 50-60 TUE WITH CLEARING SKIES IN THE AFTERNOON AND
MINIMAL DIP IN THICKNESSES.

TUE NIGHT THROUGH WED NIGHT: A SECONDARY POTENT VORTICITY MAX WILL
DIVE THROUGH THE CENTRAL MISS VALLEY TUE AND CROSS VA AND NRN NC TUE
NIGHT... HOWEVER THIS IS FAIRLY MOISTURE STARVED AND SHOULD GENERATE
LITTLE MORE THAN SOME CLOUDS. OTHERWISE WE WILL SEE HIGH PRESSURE
BUILDING IN GRADUALLY FROM THE NW THROUGH WED NIGHT... WITH A NET
RESULT OF DRY WEATHER AND NEAR TO SLIGHTLY ABOVE NORMAL TEMPS FOR
CENTRAL NC. -GIH

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 300 PM SATURDAY...

FAIRLY QUIET WEATHER FOR THE END OF THE FORECAST PERIOD AS SURFACE
HIGH PRESSURE MOVES TO THE NORTH OF THE AREA ON THURSDAY. A LITTLE
BIG COOLER THAN WEDNESDAY BECAUSE OF A SMALL EXTRA SURGE OF COLD AIR
THAT WILL MOVE THROUGH THURSDAY MORNING WITH THE PASSAGE OF THE
UPPER TROUGH AXIS. THIS SHOULD KEEP HIGHS IN THE LOW 50S BUT WITH
PLENTY OF SUN. THERE WILL BE A WARMING TREND FOR FRIDAY AND SATURDAY
AS A FAIRLY STRONG UPPER RIDGE EXTENDS UP FROM THE GULF OF MEXICO
AND HIGH PRESSURE MOVES OFFSHORE...PUTTING CENTRAL NC IN THE WARM
RETURN FLOW REGIME.

MODELS ARE NOT IN AGREEMENT ON THE HANDLING OF THE NEXT LOW PRESSURE
SYSTEM FROM WHICH AN ASSOCIATED COLD FRONT IS EXPECTED TO MOVE
THROUGH CENTRAL NC AT SOME POINT NEXT WEEKEND. THERE IS A CHANCE
THAT THE FRONT COULD MOVE THROUGH ON SATURDAY BUT WITH LITTLE
MOISTURE. REGARDLESS...TEMPERATURES WILL BE WARM AHEAD OF THE FRONT
WITH HIGHS ON SATURDAY IN THE LOW TO MID 60S...FINALLY BACK ABOVE
NORMAL FOR THIS TIME OF YEAR.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 1240 AM SUNDAY...

AN AREA OF HIGH PRESSURE EXTENDING ACROSS THE MID ATLANTIC AND
CAROLINAS WILL MAINTAIN VFR CONDITIONS TODAY. THE HIGH WILL DRIFT
EASTWARD AND OFFSHORE LATER TODAY. THUS...SFC WINDS WILL GRADUALLY
VEER FROM A NORTHERLY DIRECTION EARLY THIS MORNING TO AN EASTERLY
DIRECTION BY THIS AFTERNOON.

MID-HIGH LEVEL CLOUDS WILL INCREASE FROM THE WEST LATER
TODAY...AND THICKEN/LOWER THIS EVENING. AREAS OF LIGHT SNOW WILL
DEVELOP ACROSS THE PIEDMONT BETWEEN 03Z-08Z...EXPANDING INTO THE
COASTAL PLAIN AND SANDHILLS BETWEEN 08Z-12Z. MVFR CEILINGS AND
VISIBILITY WILL BE WIDESPREAD ACROSS CENTRAL NC AFTER 08Z.

A MIX BAG OF WINTRY PRECIP WILL OCCUR MONDAY MORNING WITH SNOW
AND SLEET ACROSS THE NW HALF...AND THE SNOW TRANSITIONING TO
FREEZING RAIN THEN RAIN ACROSS THE SE HALF. THE SNOW WILL BECOME
FREEZING RAIN THEN RAIN ACROSS THE NW HALF MONDAY AFTERNOON.
WIDESPREAD MVFR/IFR CONDITIONS WILL PERSIST INTO MONDAY NIGHT
AS NUMEROUS SHOWERS COVER THE REGION.

A COLD FRONT WILL CROSS CENTRAL NC EARLY TUESDAY...BRINGING AN
END TO THE RAIN SHOWERS. IMPROVING AVIATION CONDITIONS
ANTICIPATED TUESDAY AFTERNOON AND TUESDAY NIGHT. VFR CONDITIONS
EXPECTED WEDNESDAY INTO THURSDAY.

&&

.CLIMATE...

HERE ARE THE RECORD LOWS AND RECORD LOW MAXIMUM TEMPERATURES FOR
FEB 14TH.


       REC    YR     REC    YR
       LOW         LOW MAX
----------------------------------------------
GSO:
02/14    6   1905     22   1914

RDU:
02/14   -2   1899     27   1916

FAY:
02/14   12   1968     33   1916

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY EVENING FOR
NCZ007-021>023-038-039.
WINTER STORM WATCH FROM MONDAY MORNING THROUGH MONDAY AFTERNOON FOR
NCZ008>010-024>026-040-041-073>076.

&&

$$

SYNOPSIS...WSS
NEAR TERM...ELLIS/SMITH
SHORT TERM...HARTFIELD
LONG TERM...ELLIS
AVIATION...WSS
CLIMATE...RAH



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